HP 971A User manual

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HP 971A Multimeter
User’s Guide
Part Number 00971-90002
March 1995
© Copyright Hewlett-Packard Company 1994, 1995
All Rights Reserved

HP 971A Multimeter
Table of Contents
SafetySummary. .. .. .. .. .. .. .. 1-4
SafetySymbols . .. .. .. .. .. .. .1-4
Maximum Overvoltage Limitations...1-5
ProbesandTestLeads. .. .. .. .. 1-6
Operation. . . . . . . . . . . . . . . . . . . 1-7
Terminals,Shutter, & Test Leads...1-7
FunctionSwitch . .. .. .. .. .. .. .1-8
FunctionKeys. .. .. .. .. .. .. .. 1-9
Function Keys/Function Switch Matrix ..1-12
Display. .. .. .. .. .. .. .. .. .. 1-13
Audio . .. .. .. .. .. .. .. .. .. .1-13
CalibrationandAdjustment . .. .. .. .1-14
RequiredTestEquipment . .. .. .. .1-14
CalibrationProcedure . .. .. .. .. .1-14
Maintenance. .. .. .. .. .. .. .. .. 1-15
BatteryReplacement. .. .. .. .. .. 1-15
FuseReplacement . .. .. .. .. .. .1-15
Troubleshooting . .. .. .. .. .. .. .1-16
Cleaning . .. .. .. .. .. .. .. .. .1-16
Replaceable Parts/Accessories ....1-16
Specifications . .. .. .. .. .. .. .. .1-17
General. . . . . . . . . . . . . . . . . . . 1-17
DCVoltage. . . . . . . . . . . . . . . . . 1-17
ACVoltage. .. .. .. .. .. .. .. .1-18
DCCurrent. . . . . . . . . . . . . . . . . 1-18
ACCurrent. .. .. .. .. .. .. .. .1-19
Resistance. . . . . . . . . . . . . . . . . 1-19
Continuity . .. .. .. .. .. .. .. .. .1-19
Diode . .. .. .. .. .. .. .. .. .. .1-20
Temperature. . . . . . . . . . . . . . . 1-20
Frequency. . . . . . . . . . . . . . . . . 1-20
Adjustments. . . . . . . . . . . . . . . . . 6-1
CalibrationTable. . . . . . . . . . . . . . . 6-2
Replaceable Parts/Accessories ......6-4
Disassembly . .. .. .. .. .. .. .. .6-5
DeclarationofConformity
1-3

Safety Summary
The CAUTIONS and WARNINGS which appear on the following pages must be followed to
ensure operator safety and to retain the operating condition of the Multimeter.
1. Do not use this product beyond its specifications or for uses not intended for this product
as identified by the product functions, ranges, and hazards as indicted below.
2. To minimize possible electric shock hazard condition, connect only two leads at any one
time to any of the multimeter terminals.
3. To prevent possible electric shock hazard condition when using the current function, do not
leave one probe connected to the circuit under test and the other probe disconnected,
exposed, and readily accessible (touchable).
Safety Symbols
Indicates the operator must refer to an explanation in this manual.
Indicates terminals at which dangerous voltages may exist.
WARNING
TO AVOID ELECTRICAL SHOCK or damage to the multimeter, do not apply more than
±1000 Vdc or 1000 Vrms between any terminal and earth ground. Use caution when working with
voltages above 60 Vdc or 42 Vpeak. Ensure test leads are in good condition.
WARNING
POSSIBLE ELECTRICAL SHOCK. Do not make measurements if the case is damaged or the
rear cover is removed. Remove all electrical inputs before removing the rear cover.
WARNING
POSSIBLE ELECTRICAL SHOCK or FIRE HAZARD. Do not expose this multimeter to rain or
moisture. Do not operate the multimeter in the presence of flammable gases or fumes.
1-4

WARNING
POSSIBLE ELECTRICAL SHOCK. Calibration and performance tests are to be performed by
qualified personnel only. Do not attempt calibration or test procedures unless qualified to do so.
CAUTION
To avoid damage to the multimeter for inputs above 250 Vdc or Vac, disconnect the test leads
before changing functions. Do not exceed the maximum input limits.
Maximum Overvoltage Limitations (AC and DC Voltage Functions)
1000V
MAX indicates the maximum voltage between input terminals and earth is ±1000 V (dc or ac rms).
Do not use the multimeter on any ACV circuit where the maximum impulse overvoltage may
be more than 4000Vpk or any DCV circuit where the maximum impulse overvoltage may be
more than 2500Vpk between the COM and VOLT terminals. Excessive impulse overvoltage
can damage the multimeter voltage functions. Do not measure branch circuits (CAT 11) over
600V to earth or service panel circuits (CAT III) over 300V to earth.
Safety Summary
1-5

Function Maximum Operating Input
10 A ±10 A (dc or ac rms) / 600 V
mA or µA±500 mA (dc or ac rms) / 250 V
Diode Test, Resistance
Continuity, Temperature 660 Vrms (sinewave)
Frequency 660 Vrms (5 Hz to 10 kHz)
100 Vrms (10 kHz to 100 kHz)
V ±1000 Vdc or Vrms (sinewave)
Probes and Test Leads
1. Always inspect probes before use. Do not use test leads whose insulation has cuts,
cracks, or other damage that may result in reduced electric shock protection.
2. Keep insulation surface clean between the probe tip connector and the finger guards.
3. If probes other than the ones specified are to be used with the multimeter, be sure the
probes and their leads are rated for the voltage and current to which they will be subjected.
Do not exceed the voltage ratings for the multimeter.
4. Probes supplied with this multimeter are rated for use up to 1000Vrms or Vdc.
Safety Summary
1-6

Operation
Terminals, Shutter, & Test Leads
RED LEAD
Current Measurements
(0 A to 10 A)
RED LEAD
Current Measurements
(0 to 400 mA)
BLACK LEAD
COMMON
ALL Measurements
RED LEAD
DC & AC Voltage,
Diode, Resistance, Frequency,
Temperature, and Continuity
Measurements
SAFETY SHUTTER
Slide up to open shutters
for current measurement
inputs. Must have the
function switch in one of
the Current Measurement
positions to open shutter.
Close shutter to change
function switch to any
other measurement
function.
1-7

Function Switch
Switch
Position Display
10A DC Current
(10 mA to 10 A) AC Current (10 mA to 10 A)
mA DC Current
(10 µA to 0.4 A) AC Current (10 µA to 0.4 A)
µADC Current
(0.1 µA to 4 mA) AC Current (0.1 µA to 4 mA)
Diode Test
(0 to 2 V) Auto Diode Test
( 0 to ±2 V)
ΩResistance
(0.1 Ωto 40 MΩ)Continuity (alarm at < 20 Ω)Temperature in °F
(-112°F to 302°F) Temperature in °C (-80°C to 150°C)
Hz Frequency
(5 Hz to 99.9 kHz)
mV DC volts
(100 µV to 400 mV) AC volts (100 µV to 400 mV)
VDC Volts
(1 mV to 1000 V)
VAC volts
(1 mV to 1000 V)
Operation
1-8

Function Keys
Power
Automatic power off/power save after 30 minutes. Alarm sounds 30 seconds before power off.
Power off if input < 80 V or < 400 mA. Power save if input > 80 V or > 400 mA, last measurement
displayed, power consumption is reduced. Press any key or change any function to cancel. Defeat
by holding the key for 2 seconds while applying power.
Relative/Percent
Press Action Main Display Secondary
Display
Makes the last displayed
measurement the reference Each measured value relative to the reference value (difference) Range
Calculates the percentage change
from the reference Each measured value as a percent change of the reference value Range
Cancels the Relative/% function Measured value Range
Perform a zero adjust on the 400 Ω range and displayed value is less than 99 by shorting the test leads and
pressing this key. Cycle power to erase the stored zero adjustment.
Operation
1-9

Minimum/Maximum 1
Press Action Main Display Secondary 2
Display
Begin recording of
minimum and maximum values Each measured value Elapsed time
Display recorded maximum Maximum measurement Time of maximum
Display recorded minimum Minimum measurement Time of Minimum
Display last recorded measurement Latest measurement Elapsed time
Pause recording of
minimum and maximum values 3Holds display Total elapsed time
Resume recording of
minimum and maximum values Each measured value Elapsed time
Press and hold 1 second to cancel ——
1Automatic power off and auto ranging are disabled when Min/Max is selected. Bargraph will indicate
and hold maximum values.
2Time is recorded and displayed in minutes up to the maximum recording time of 1999 minutes.
Recording will stop at the maximum time.
3The H annunciator is displayed when Min/Max recording is paused.
Average
Press Action Main Display Secondary Display
Makes the displayed measurement the
average of the last eight measurements Average value of last eight measurements Range
Disables the averaging of
measurements Each measurement Range
Operation
1-10

Hold/Auto-Hold
Press Action Main Display Secondary
Display
Holds the measurement value in the display Measurement value when
hold pressed Range
Enters Auto-Hold function 1Input value Range
Cancels Hold function Measurement value Range
1Auto-Hold Operation. When measurement becomes stable, multimeter will beep and save the stable
reading. Removing probe from measuring circuit will display and hold the last stable reading.
Range
Press Action Main Display Secondary
Display
Changes from auto-ranging to manual ranging Measurement value Range
Change manual range
UP once with each keypress 1Measurement value Range
Returns to auto-ranging when key is
held for 1 second Measurement value Range
1When upper range is reached, the sequence begins again at the lowest range.
Select
Press this key to use the functions indicated in blue on the multimeter. See table on page 1-8.
Hold this key to test display when turning meter on.
Operation
1-11

Function Keys and Function Switch Matrix
Function Relative %
(Percent) Min/Max 5Average Data Hold4Auto-Hold Range
µA, mA •••••••
10A ••••••
•• • •
•
Ω•1••••••
•
°F, °C2•• •
Hz2••3
mV •• • • • •
mV •• • • • •
V •••••••
V •••••••
1Invokes zero adjust when display is less than 9.9 Ω.
2Bargraph not available.
3Changes input attenuator, frequency is always auto range.
4Bargraph updates with input value.
5Secondary display shows elapsed time (in minutes).
Operation
1-12

Display
Audio
Power on
First beep at power on.
Second beep when beginning to make measurements.
Single beep
Indicates any valid function key press.
Indicates a new High or Low value recorded when in Min/Max function.
Steady repeating beep
Indicates when measurement is steady when using Auto-Hold function.
Rapid repeating beeps
Indicates wrong input terminals used for function selected.
Indicates an overload condition at the measurement terminals.
Continuous tone
Indicates a resistance of < 20 Ω when using the Continuity function.
Auto Power Off/Auto Power Save
Pairs of beeps for 30 seconds.
Long beep just before power off.
Cancel by changing function switch position or pressing any key.
Low Battery indicator
Replace batteries when on.
Secondary Display
Shows:
Range (most functions)
Elapsed time (Min/Max)
Main Display
(Annunciators shown inside front cover)
Number of digits is set by range and function
Displays O.L to indicate an overload condition
Entire display flashes if:
Input overvoltage or
During Amps fuse check
Bargraph
Active for all functions except:
Temperature and Frequency
Operation
1-13

Calibration and Adjustment
Required Test Equipment
The source used for the calibration should have an output accuracy as good or better than
that listed in the specifications.
Calibration Procedure
Environmental range for calibration: 23°C ±5°C, < 80% RH
Calibration interval: 1 Year
1 Disconnect all inputs from the multimeter and open the case as shown on page 6-5.
2 Install new batteries (described below) and close the cover. Turn the multimeter on and allow a
30 minute warm-up. Open the case.
3 Set the multimeter function and range and the source output to the values specified at each step
in the calibration table on page 6-2.
4 When appropriate, make the adjustments indicated in the calibration table to bring the multimeter
display within the limits.
CAUTION
Dangerous voltages are present during the calibration procedure. Calibration should only be
performed by qualified service technicians. Use a non-conductive adjustment tool.
1-14

Maintenance
Operator protection from electric shock hazard is provided by a double insulated enclosure.
Refer to pages 1-4 and 1-5 for maximum voltage specifications. When servicing, use only
specified replacement parts.
Battery Replacement
Replace the battery when the symbol appears in the display or before calibration. Replace
both batteries at the same time. Use high-quality type AA alkaline (IEC LR6) batteries.
Remove the batteries if the multimeter is to be stored for extended periods of time. Refer to
the disassembly drawing on page 6-5.
Fuse Replacement
Fuse locations are shown in the diagram on page 6-5. Fuses are listed in the replaceable
part list on page 6-4. See fuse check procedure in Troubleshooting table below.
CAUTION
For continued protection use only the specified manufacturer part number or HP part number
fuse for replacement purposes.
1-15

Troubleshooting
Problem Possible Cause Suggested Action
Unit won’t turn on Dead Batteries Replace batteries
Unit won’t turn off Input limit exceeded Remove test leads and press any key to reset.
Display flashes
and
Rapid beeps
Input limit exceeded Remove test leads and press any key to reset.
Test leads in wrong
terminal for measurement
function Change test leads or function switch position
Battery Annunciator on Low battery voltage Replace batteries
Unable to measure
current
10 A or mA - µAOpen input protection fuse Check fuse. Connect test lead between V input
terminal and 10A or 10 mA µA terminal. Select
10A or 10mA range, unit will rapidly beep if
fuse is OK. Replace fuse if no beep.
Cleaning
Wipe instrument with a soft rag dampened with soap and water. Do not immerse in water.
Do not use any chemical cleaner or solvents.
Replaceable Parts/Accessories
Refer to the table on page 6-4.
Maintenance
1-16

Specifications
Calibration period: one year minimum. Specifications apply at 23°C ±5°C, < 80% RH
Accuracy = ±(% of reading + number of digits).
Temperature Coefficient = Accuracy X 0.1/°C (-10°C to 18°C; 28°C to 55°C)
General
Do not expose product to moisture or rain. Do not use product in flammable atmosphere.
Operating Temperature: -10° to 50°C.
Humidity: 0°C to 40°C / 80% RH max, 40°C to 50°C / 70% RH max (no condensation).
Storage Temperature: -25° to 60°C / 70% RH max (no condensation).
Display reading rate: Approximately 2.3 times/second (Frequency 1/second)
Bargraph reading rate: Approximately 23 times/second
Battery life: Approximately 1000 hours
DC Voltage
Range Resolution Accuracy Input Resistance
400 mV 100 µV
± (0.3% + 1)
10 MΩ
4.0 V 1 mV 11 MΩ (nominal)
40 V 10 mV 10 MΩ (nominal)
400 V 100 mV
1000 V 1 V
Normal Mode Rejection Ratio (NMR): > 60 dB @ 50 or 60 Hz
Effective Common Mode Rejection Ratio (CMR) 1 k Ωimbalance: > 120 dB @ 50 or 60 Hz
1-17

AC Voltage (Average responding, calibrated to display rms)
Range Resolution Accuracy Input Impedance (nominal)
40 Hz to 500 Hz 500 Hz to 1 kHz
400 mV 0.1 mV
±(1% + 2) ±(1.5% + 4)
10 MΩ< 50 pF
4 V 1 mV 11 MΩ< 50 pF
40 V 10 mV 10 MΩ< 50 pF
400 V 100 mV
1000 V 1 V Not Specified
Common Mode Rejection Ratio (CMR)1 kΩimbalance: > 60 dB @ DC to 60 Hz
Response time: 2 seconds maximum
DC Current
Range Resolution Accuracy Input
Resistance Maximum Input
400 µA100 nA ±(0.5% + 2) < 550 Ω± 0.5 A (fused)
4000 µA1µA±(1% + 2)
40 mA 10 µA< 8 Ω
400 mA 100 µA±(1.2% + 2)
10 A 10 mA < 0.05 Ω±15 A (fused)
Specifications
1-18

AC Current (Average responding, 40 Hz to 500 Hz, calibrated to display rms)
Range Resolution Accuracy Input
Resistance Maximum Input
400 µA100 nA
±(1.5% + 5)
< 550 Ω0.5 Arms (fused)
4000 µA1µA
40 mA 10 µA< 8 Ω
400 mA 100 µA
10 A 10 mA < 0.05 Ω15 Arms (fused)
Resistance
Range Resolution Accuracy Test Current Maximum
Open Circuit Voltage
400 Ω100 mΩ±(0.5% + 1) 1< 0.8 mA < 3.2 V
4.0 kΩ1Ω
± (0.5% + 1)
< 80 µA
< 1.1 V
40 kΩ10 Ω < 10 µA
400 kΩ100 Ω < 1.1 µA
4.0 MΩ1 kΩ< 110 nA
40 MΩ10 kΩ±(1.0% + 1)
1After zero adjust of input leads. Zero adjust range up to 9.9 Ω.
Response time: 400 Ωto 400 kΩ— 2 seconds, 10 MΩto 40 MΩ— 10 seconds.
Continuity
Measurement Current: 0.8 mA maximum Open circuit voltage: < 3.2 Vpeak
Displayed resistance: 0 Ωto 400 ΩInput protection: 660 Vrms (sinewave)
Alarm: Tone when input < 20 Ω Resolution: 100 m Ω
Specifications
1-19